Rust-inhibiting lubricating composition



Patented Feb. 1, 1950 UNITED STATE BUST-.INHIBITING LUBRIOATING COMPOSITION Herman D. Kluge, Wapplngers Falls, N. Y., al-

signor to The Texas Company, New York, N. Y., a corporation of Delaware No Drawing. Application May 14, 1946, Serial No. 669.583

2 Claims. (Cl. 252-483) This invention relates to a method of protecting metal surfaces against corrosion and rust formation in the presence of water and to an improved rust preventive composition.

It is recognized that the rusting of metal surfaces, and particularly the ferrous metals and alloys thereof, presents a serious problem in the maintenance and operation of industrial equipment and metal structures. This problem is most pronounced in the lubrication and preservation of machine and engine parts or other finished metal surfaces which are designed for operation under conditions of close space tolerances. It has recently been proposed to protect such metal surfaces from the formation of rust, e. g., ferric oxide, by applying to the metal surface a polar film of a dicarboxylic acid possessing one or more hydrocarbon ether radicals branching from the carbon chain linking the carboxylic group, in accordance with the disclosures of U. S. Patents Nos. 2,371,142 and 2,371,143, granted to Emmett R. Barnum and Ernest W. Zublin on March 13, 1945. Although many of the particular dicarboxylic acids proposed satisfactorily prevent the formation of rust or ferric oxide on metal surfaces subjected to the action of oxygen and water,

they possess certain disadvantages which in most instances ofiset their rust inhibiting properties.

the rust-inhibiting characteristics of these acids.-

It has now been discovered that a polar film of a dicarboxylic acid possessing at least 12 carbon atoms and containing at least one tertiary alkyl radical linked to the carbon'chain between the carboxyl groups through an element such as oxygen, sulfur, selenium or tellurium, provides effective rust protection to the metal surfaces r 2 ing or brush application, to exposed metal Burfaces such as steel structures and metal equipment for transit or storage.

The acids of the invention may be further described as the dicarboxylic acids containing at least 12 carbon atoms and possessing the following descriptive formula:

OOH

wherein n and m are integers of at least one, X is an element of the class of oxygen, sulfur, selenium, or tellurium, R is tertiary alkyl radical, Y is either hydrogen or a hydrocarbon radical, and r is 0 or a whole number as required to satisfy the valence of 4 of each carbon atom of C... n is preferably greater than m and is usually within the range of 2 to 8, while 111. is usually within the range of 1 to 4. Thus, a tertiary alkyl ether radical (Rx) is attached to at least one of the number of carbon atoms in the chain connecting the carboxyl groups. X is preferably a sulfur atom and when more than one tertiary alkyl "ether" radical is contained in the molecule, X may be the same or different elements of the class of O, S, Se or Te in the various "ether radicals.

The majority of these aliphatic dicarboxylic acids exist in stereo-isomeric form and for purposes of the invention the cis form of the acid or the ones in which the carboxyl groups are in a plane symmetrical configuration are preferred. Furthermore. it is preferable that the acids contain a sufiicient number of carbon atoms, in the molecule to render them soluble or miscible in the oleaginous vehicle in which they are incorporated; The oleaginous vehicle referred to throughout the specification and claims is meant to include the hydrocarbon oils, fats, fatty oils, greases, lubricants, rust-proof bases, etc., which may be used as the medium of application of and particularly ferrous metals and prevents the tion and lubrication of friction surfaces are required. However, they may also be incorporated in other oleaginous vehicles which serve as a the rust inhibitor to the metal surfaces.

The amounts of acid which are incorporated in the oleaginous vehicle naturally depend upon the type of protection and the service to which they are applied. In general, it may be stated that amounts not materially greater than 3% by weight of the oleaginous vehicle as applied to the metal surfaces may be used with advantageous results. In lubricating compositions this amount may be substantially decreased and still provide' adequate protection. Ranges of proportions between 0.01 and 1.0% by weight of the medium for applyin the inhibitor. e. 8.. pray- 'dicarboxylic acid in a lubricating oil may be used an e acid.

'liertiary-dodecyl thiosuccinic acid. Alkyl I thiosuccinic acid...

. 3 where maximum rust prevention and minimum interference with the lubricating properties of the lubricant are required. It is to be expected that larger amounts of the dicarboxylic acid win be required in the preparation of the so-called rust-proof compounds where the sole Motion of the composition is to provide protection to exposed metallic surfaces and in the preparation lustrative of the advantages of the dicarboxylic acids of the inventiongand are not to be considered as limitations thereofg, In this test a.

polished steel specimenis suspended in an agitated mixture of 300 cos. .of the oil to be tested and 30 cos. ofa synthetic sea water. The oilsea water sample is maintained at 140 I". over, an oil bath for 48 hours. after which time. the

steel specimen is removed, allowed to drain, and washed with precipitated naphtha and acetone, and the amount of rust observed. The synthetic sea water added to the test oil contains the following composition:

137 milligrams of a cream-colored powdery film were obtained which analysed as follows:

mm 5 Iound Is (Add): 1'61 (Acid) l e-12s 9.66 12.5 I-LMM 11.1 10.73

These results indicate that this heavy film is the result oi the reaction of the iron and the normal alkyl thi'osuccinic acid and is probably a mixture of the iron basic salt of the dicarbox- *llylic acid. It may readily be seen that a buildup of'insoluble reaction products such as obis particularly detrimental to the lubrieating function of the oil on friction surfaces.

Obviously many modifications and variations :0 of the invention, as hereinbefore set forth, may

"be made-without departing from the spirit and -scope thereofgand therefore only such limitations should'be imposed as are indicated in the appended claims.

Iclaim:

1; A "rust-inhibiting lubricating composition consisting essentially of an oleaginous liquid having lubricating properties as the predominant constituent, and (ml-3.0% by weight on the '30 'basis of the olea'ginous liquid of a tertiary do- :decyl thiosuccinic acid suiiicient to inhibit the Grams per liter Magnesium chloride (Mg 012. GHzO) 11.0 formation on a steel specimen immersed in said Anhydrous'calcium chloride (CaCh) 1.2 composition in the presence of salt water of both Anhydrous sodium sulfate (Nazsoi) 4.0 ferric oxide rust, as well as a cream-colored pow- Bodlum chloride (NaCl) 25.0 dery illm which results from reaction of the iron In these particular tests a solvent-refined, acidtreated and filtered lubricating oil was used as the base oil in which was incorporated 0.03% by weight of the thiosuccinic acid derivatives. The results obtained are as follows:

Rusting test Additive Appearance of Steel Specimen n-Dodecyl (lauryl) thiocream-colored powdery film.

\ Average molecular weight 01 alkyl group-C".

The heavy powdery film obtained from the nalkyl derivatives remained on the steel specimen even after removal of the test oil and wash- Pin points of ferric oxide met-heavy loi tween the carboxyl'groups.

1A rust-inhibiting lubricating composition according to claim 1, wherein the oleaginous liq aid is a solvent-refined acid-treated mineral lu- :"br icating oil, and the tertiary dodecyl thiosuccinic acid'is present in a proportion of 0.01-i.0%

by weight based on the oil.

D. KLUGE.

REFERENCES CITED The following references are of record in the file ofzthis patent:

UNITED STATES PATENTS "Number Name Date 2,284,241 Werntz May 26, 1942 2,293,580 Walker Aug. 18, 1942 2,334,158 Fuchs et al Nov. 9, 1943 2,368,606 White Jan. 30, 1945 2,369,641 Barnum Feb. 20, 1945 2,371,142 Barnum et al Mar. 13, 1945 3,371,143 Barnum et a1. Mar. 13, 1945 

1. A RUST-INHABITING, LUBRICATING COMPOSITION CONSISTING ESSENTIALLY OF AN OLEAGINOUS LIQUID HAVING LUBRICATING PROPERTIES AS THE PREDOMINANT CONSTITUENT, AND 0.01-3% BY WEIGHT ON THE BASIS OF THE OLEGINOUS LIQUID OF A TERTIARY DODECYL THIOSUCCINIC ACID SUFFICIENT TO INHIBIT THE FORMATION ON A STEEL SPECIMEN IMMERSED IN SAID COMPOSITION IN THE PRESENCE OF SALT WATER OF BOTH FERRIC OXIDE RUST, AS WELL AS A CREAM-COLORED POWDERY FILM WHICH RESULTS FROM REACTION OF THE ION WITH A N-DODECYL THIOSUCCINIC ACID HAVING THE TERTIARY DODECYL THIOCUCCINIC ACID HAVING THE TERTIARY DODECYL RADICAL LINKED THROUGH THE SULFUR ATOM TO THE CARBON CHAIN OF THE SUCCINIC ACID BETWEEN THE CARBOXYL GROUPS. 